| Copper is usually associated with lead minerals, of which enters the lead bullion in the pyrometallurgical process of lead. It's usually separated from the lead bullion in the form of copper sulfide (called Pb-Cu matte) by adding sulfur in the pyro-refining of lead bullion. Pb-Cu matte copper usually contains lead, silver and other valuable metals besides copper. So far, it always treated by pyrometallurgy which has a lot of disadvantages such as low recovery of metals, high environmental pollution, long flow, high investment and cost etc. Therefore, the development of a high efficiency and cleaning metallurgical technology to treat such materials has important practical significance.It takes Pb-Cu matte and mixed materials as materials in experiments. A new technology of hydrometallurgy for treating such materials by pressure oxidative leaching and electrowinning directly is proposed, and the theory and experiment of the key process were investigated. The main contents of the paper contain as follows:1. The thermodynamics of pressure oxidative leaching of Pb-Cu matte and mixed materials was analyzed by the E-pH diagrams of Cu2S-H2O system at 423K and MeS-H2O system at 298K.2. The leaching conditions of Pb-Cu matte were studied. The effects of leaching time, oxygen partial pressure, L/S ratio, materials granularity, acid addition, leaching temperature, agitation speed and initial Cu2+ concentration on the extraction of copper and iron at pressure oxidative leaching of Pb-Cu matte by new solution which no Cu2+ and waste electrolyte were investigated systematically. The effect of initial Cu2+ concentration, L/S ratio and materials granularity are insignificant compared to the other reaction parameters. The best found conditions are: leaching time 2～3 h, oxygen partial pressure 0.8 MPa, total pressure 1.2～1.3 MPa, acid addition theoretical mass, leaching temperature 140～150℃, agitation speed 600 rpm, L/S ratio 10:1 and materials granularity 55% smaller than -100 mesh. Under these conditions,>97% Cu is extracted with the concentration of iron in solution<5g/L. The leaching residue is about 30% of the initial mass, the recovery of lead and silver is close to 100% and 98% respectively, the iron is more than 60% as deposition in residue and the yield of sulfur is about 25% of total sulfur mass.3. It is very difficult to separate Pb-Cu matte from slag which contains copper in the pyrometallurgical process of lead. So, it has to put the Pb-Cu matte and slag (called mixed materials) together into considered. The pressure oxidative leaching of mixed materials with high silicon was studied systematically. The filtration of magma is very difficulty after Pox leaching. The technique for improving the filtration performance is achieved by experiments. It can resolve the difficulty of the filtration by adding composition flocculation reagent A, CaCO3 and composition flocculation reagent A after the leaching by new solution and waste electrolyte respectively. Under the best conditions, the filtration rate is 220～550 L/m2·h, the Cu extraction is more than 90% with the concentration of iron in solution <2g/L, the leaching residue is about 55～75% of the initial mass, the recovery of lead and silver is close to 100% and 95% respectively, the iron is more than 80% as deposition in residue and the yield of sulfur is about 25% of total sulfur mass.4. The experiment of copper electrowinning was studied. The best found conditions are:the pole pitch 4cm, the temperature 25～40℃, the current density 220A/m2, the circuit speed of the electrolyte 250L/m3·h, the terminal copper content of the waste electrolyte 25g/L, the concentration of iron <10g/L and the amount of additive is 20-70g/t·Cu. Under these conditions, the current efficiency is greater than 90%, the tank voltage is 2.0-2.1V and the cathode copper are up to CATH-2. 5. In order to prove the stability of the process, the circulation experiments of leaching, electrowinning and leaching by waste electrolyte were carried out. It achieves some parameters through 5 circulation experiments.(1). Cu extraction rate >97.48%(2). Yield of residues～30%(3). Lead recovery rate 100%(4). Silver recovery rate >97.55%(5). Iron as deposition >59.68%(6). Yield of sulfur～23%6. The kinetics of pressure oxidative leaching of Pb-Cu matte was studied. The kinetics equations of materials granularity, total pressure, leaching temperature and acidity are found respectively. The apparent reaction activation energy is 21.03KJ/mol which indicates that the pressure oxidative leaching of Pb-Cu matte is driven by mix-controlled. The mathematics model of Cu extraction from Pb-Cu matte by pressure oxidative leaching is found.a(%)=100×{1-[1-1/r0exp(-1.5856-2608.461/T+0.6461n P+0.2281nC)t]3}The model was proved by 65 experiments. It indicates that the calculated consequences and experimental consequences are inosculation very well.The innovations of the paper are as follows:(1). A new technology route for Pb-Cu matte and mixed materials is proposed. A new process of hydrometallurgy for Cu extraction from Pb-Cu matte and mixed materials is researched and developed, and the patent is applied also.(2). The technology conditions of pressure oxidative leaching of Pb-Cu matte and mixed materials were investigated systematically. It achieves high copper extraction rate. (3). The technique for improving the filtration performance of magma which is very difficult filtration after Pox leaching of mixed materials with high silicon and iron is achieved by experiments.(4). The copper electrowinning of low acidity solution was studied and the cathode copper which is up to CATH-2 is achieved.(5). The E-pH diagrams of Cu2S-H2O system at 423K is constructed firstly. The kinetics of pressure oxidative leaching of Pb-Cu matte was studied. The kinetics equations of ore granularity, total pressure, leaching temperature and acidity are found respectively. The mathematics model of Cu extraction from Pb-Cu matte by pressure oxidative leaching is found. |
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